The suspect is identified as Curtis Smith of Coatesville, Pa.
Investigators say Smith entered the Justice Center around 12 p.m. with a knife, and attacked a sheriff's deputy, slashing him.
The district attorney said another deputy opened fire, shooting Smith.
Smith was rushed to Paoli Hospital but later died.
The deputy who was attacked is being treated for injuries to his arm and hand.
The deputy who opened fire is being interviewed.
District Attorney Tom Hogan revealed Smith's connection to the White House incident. It happened back in March and ABC station WJLA reported he was charged at the time with unlawful entry.
VIDEO: Witness describes shooting scene
David Widdowson tells Action News he was sitting outside the Justice Center when he heard three gunshots.
"I seen one guy get wheeled out on a stretcher, and a police officer also get wheeled out on a stretcher," he said. null